In localization microscopy, subnanometer precision is possible but supporting
accuracy is challenging, and no study has demonstrated reliable traceability to
the International System of Units (SI). To do so, we measure the positions of
nanoscale apertures in a reference array by traceable atomic-force microscopy,
creating a master standard. We perform correlative measurements of this
standard by optical microscopy, correcting position errors from optical
aberrations by a Zernike calibration. We establish an uncertainty field due to
localization errors and scale uncertainty, with regions of position
traceability to within a 68 % coverage interval of +/- 1.0 nm. These results
enable localization metrology with high throughput, which we apply to measure
working standards, validating the subnanometer accuracy of lithographic pitch